Diseases and Conditions

What is type 1 diabetes?

In type 1 diabetes, the body can’t make insulin. Insulin is needed to help glucose enter cells for energy. Without insulin, glucose builds up in the blood. This causes high blood glucose or high blood sugar. Type 1 diabetes may also be known as:

Insulin-dependent diabetes mellitus (IDDM)

Juvenile diabetes

Brittle diabetes

Sugar diabetes

Type 1 diabetes accounts for 5% of all diagnosed cases of diabetes in the U.S. Type 1 diabetes most often develops in children or young adults, but can start at any age.

What causes type 1 diabetes?

The cause of type 1 diabetes is unknown. It’s thought that genetic and environmental factors are involved.

The body's immune system attacks and destroys the cells in the pancreas that make insulin. Insulin lets glucose to enter the cells for energy. When glucose can’t enter the cells, it builds up in the blood. This deprives the cells of nutrition. It also results in high blood sugar. People with type 1 diabetes must take daily insulin shots and regularly check their blood sugar levels.

What are the symptoms of type 1 diabetes?

Type 1 diabetes often appears suddenly. Symptoms may include:

Unusual thirst

Frequent passing urine

Extreme hunger but loss of weight

Blurred vision

Nausea and vomiting

Extreme weakness and fatigue

Irritability and mood changes

In children, symptoms may be similar to those of having the flu.

The symptoms of type 1 diabetes may look like other conditions or health problems. Always see your healthcare provider for a diagnosis.

How is type 1 diabetes diagnosed?

There are several ways to diagnose diabetes. It is best for the tests to be repeated on a second day to make sure of the diagnosis.

A1C. The hemoglobin A1C test measures your average blood glucose for the past 2 to 3 months. Diabetes is diagnosed at an A1C of greater than or equal to 6.5%.

Fasting plasma glucose (FPG). This test checks your blood glucose levels after fasting overnight. You may have water before this test is done, but nothing else. Diabetes is diagnosed at a fasting blood glucose of greater than or equal to 126 mg/dl.

Oral glucose tolerance test (OGTT). This is a 2-hour test that checks your blood glucose levels before and 2 hours after you drink a sugary drink. This test tells your doctor how your body processes glucose. Diabetes is diagnosed at a 2-hour blood glucose of greater than or equal to 200 mg/dl.

Random glucose test. This blood test is done at any time of the day. Diabetes is diagnosed at blood glucose of greater than or equal to 200 mg/dl with the symptoms of hyperglycemia or hyperglycemic crisis.

Insulin and c-peptide levels. Levels of these will be low or normal with type 1 diabetes, but high with type 2 diabetes.

Antibody levels. People with newly diagnosed type 1 diabetes will usually have high levels of antibodies against certain proteins found in the pancreas.

How is type 1 diabetes treated?

Your healthcare provider will figure out the best treatment based on:

How old you are

Your overall health and medical history

How sick you are

How well you can handle specific medications, procedures, or therapies

How long the condition is expected to last

Your opinion or preference

If you have type 1 diabetes, you will need daily shots of insulin to keep your blood sugar level in normal ranges. Other parts of treatment may include:

Eating a diet to help manage blood sugar levels

Exercising to help the body use blood sugar efficiently

Monitoring blood sugar levels several times a day, as directed by your healthcare provider, and learning how to adjust your meals and insulin dose accordingly.

Having regular hemoglobin A1C testing. This is recommended at least twice a year or more often if your blood sugar level stays too high.

Research is underway to find better ways to manage diabetes. This includes looking for other way to take insulin such as through inhalers, pills, or pumps. Researchers have also identified some genetic markers for type 1 diabetes. Pancreas and islet cell transplants are considered experimental treatment.

What are the complications of type 1 diabetes?

Type 1 diabetes may cause the following:

Hypoglycemia. This is low blood sugar, sometimes called an insulin reaction. It occurs when blood sugar drops below 70 mg/dl, usually when the previous insulin dose was too high.

Hyperglycemia. This is high blood sugar that occurs when the body has too little insulin. It can be a sign that diabetes is not well controlled.

Ketoacidosis. When your body doesn't have enough insulin to use glucose for energy, it creates ketones. Ketones are a chemical that breaks down fats for energy. When ketones build up to high levels, it is a life threatening condition which can lead to coma or death.

Long-term complications of uncontrolled type 1 diabetes include:

Heart disease

Kidney disease

Eye problems

Nerve problems

Foot problems

Key points

Type 1 diabetes is an immune system disorder in which the body's immune system destroys, or tries to destroy, the cells in the pancreas that make insulin.

When glucose can’t enter the cells, it builds up in the blood. This deprives the cells of nutrition.